Lactucin- obtained from the dried milky juice of Lactuca virosa L. (Asteraceae)

2.6.3 Lactucin

Biological Sources It is obtained from the dried milky juice of Lactuca virosa L. (Asteraceae) (Bitter Lettuce; Wild Lettuce); and from the plant of Cichorium intybus L. (Compositae).

Chemical Structure

[3aR – [3aα, 4β, 9aα, 9bβ)]-3,3a,4,5,9a,9b-Hexahydro 4-hydroxy-9-(hydroxymethyl)-6-methyl-3-methyl-eneazuleno [4, 5-b] furan-2, 7-dione; (C₁₅H₁₆O₅).

Isolation Lectucin may be isolated by the method suggested by Schenck et al.*

Characteristic Features

1. It is obtained as crystal from methanol which sinters at 218°C and has mp 228-233°C.

2. It exhibits specific optical rotation [α]_D + 49° (C = 0.90 in methanol); and +77.9° (C = 3.44 in pyridine).

3. It has uv_max: 257 nm (ε 14,000).

4. It is found to be soluble in water, ethanol, methanol, ethyl acetate, anisol and dioxane.

Identification Tests It may be identified from its derivative:

Lectucin para–hydroxyphenylacetate hydrate (C₂₃H₂₂O₇) (Intybin; Lactucopicrin;): It is obtained as crystals from water which get decomposed at 148-151°C. It shows specific optical rotation [α]_D17.5 + 67.3° (pyridine)

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* London et al., J. Chem. Soc., 3431, 1950.

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